1. Field of the Invention
This invention relates to a resin composition which has excellent moldability and gives molded articles having excellent heat resistance, solvent resistance and mechanical properties, and to molded articles therefrom. More specifically, it relates to a resin composition consisting essentially of a modified polyphenylene ether, a polyphenylene sulfide and a polyisocyanate, and to molded articles therefrom.
2. Description of the Prior Art
It is well known that polyphenylene ether resins are extensively used as engineering plastics because of their excellent heat resistance, rigidity and electrical properties, but have the serious defect of poor solvent resistance and moldability.
On the other hand, polyphenylene sulfide resins are known to have excellent heat resistance, solvent resistance, electrical properties, mechanical properties, dimensional stability and fire retardancy, and have recently attracted attention. These properties of the polyphenylene sulfide can be improved by combining it with a fibrous reinforcing material such as glass fibers and carbon fibers or an inorganic filler such as talc, clay and silica, and such composite materials have found extensive use in electrical and electronic component parts and machine structural parts. However, the polyphenylene sulfide has a low degree of polymerization and is difficult to mold. Molded articles from it lack tenaciousness and are brittle. Molded articles of polyphenylene sulfide reinforced with glass fibers tend to undergo warpage.
It was proposed to blend polyphenylene ether with polyphenylene sulfide to prepare a resin composition having improved moldability and fire retardancy (Japanese Patent Publication No. 34032/1981). In this resin composition, an improvement in the moldability of the polyphenylene ether is noted. But since the compatibility between the polyphenylene ether and the polyphenylene sulfide is low, molded articles prepared from the composition have a poor appearance and degraded mechanical properties. Furthermore, when this molded article is contacted with a solvent, the polyphenylene ether and the polyphenylene sulfide are completely separated from each other, and the solvent resistance of the molded article is extremely low.
To improve the compatibility between the polyphenylene ether and the polyphenylene sulfide, a resin composition comprising these and an epoxy resin was proposed (see Japanese Patent Publication No. 11063/1985). With this composition, the compatibility between the polyphenylene ether and the polyphenylene sulfide is improved to some extent, but is still not fully satisfactory. Furthermore, a molded article from it does not have sufficient mechanical properties, and the solvent resistance of this article is not at all improved.